list_principles

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The readOnlyHint annotation already tells the agent this is a safe read, so the description only needs to add context. It does disclose the return shape at a high level ('principle summaries and available parts'), but says nothing about pagination or what the default limit of 20 implies for large result sets.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with the primary action, with the filtering option and return value packed efficiently. Nothing is wasted, though it is sparse rather than deliberately structured.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The mention of return contents partially covers the absence of an output schema, which is a plus. However, for a three-parameter tool with low schema coverage, the undefined limit and locale parameters leave an agent under-informed about result volume and language behavior.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is only 33%: 'part' is documented, but 'limit' and 'locale' are bare. The description mentions the part filter but adds no meaning beyond the schema and says nothing about limit or locale behavior, so it fails to compensate for the coverage gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description gives a specific verb and resource ('List all UX/UI principles') plus the filtering option, so an agent knows this is an enumeration tool. It does not distinguish itself from close siblings such as search_principles or get_flow_principles, which leaves the boundary ambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'or filter by part' implies when the filter is useful but states no explicit when-to-use or when-not-to-use rule. With search_principles and get_principle in the sibling list, the agent gets no guidance on why it would list instead of search.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.